The chemo- and regiospecificity of nucleophilic additions to pi-allyl metal complexes provide the basis for a new, general, facile route to spirocyclics. Our focus in the development of this synthetic methodology is on the preparation of those carbo-, aza- and oxa-spiro systems which occur in natural materials. The potential utility of this approach in the synthesis of natrual products is demonstrated in its application to the preparation of the proaporphine alkaloid, amuroline and the harringtonine, cephalotaxine. The impetus for this work is due to the pharmacological properties of spirocyclic natural products which include for amuroline, cholinesterase inhibition, neuromuscular blocking and anesthetic activity and for cephalotaxine derivatives, significant inhibitory activity against lymphoid leukemia L1210 and P388 leukemia in mice. The scant supplies of these materials available from natural sources and the need for bio-assay of structural derivatives require their synthetic preparation. The alternative product to the spirocyclics in the key metal catalyzed cyclization are anti-Bredt olefins which may be stabilized because of interaction with the metal. The ability of a metal to interact with a skewed pi-system will be evaluated as well as the synthetic utility of these intermediates.